Adam has not been playable in any of his three game appearances.
War of the Gems
Adam functions as the main NPC that ferries the player from stage to stage in an effort to gather the infinity gems.
Marvel Super Heroes
In Juggernaut's ending of Marvel Super Heroes, Adam claims the gauntlet for his own after Thanos's defeat. He then sends Juggernaut back to Earth.
Adam Warlock's current video game role is the Eternity Splinter vendor in Marvel Heroes.